An unexpected rhenium(IV)–rhenium(VII) salt: [Co(NH3)6]3[ReVIIO4][ReIVF6]4·6H2O

Abstract

The title hydrated salt, tris[hexaamminecobalt(III)] tetraoxidorhenate(VII) tetrakis[hexafluoridorhenate(IV)] hexahydrate, arose unexpectedly due to possible contamination of the K2ReF6starting material with KReO4. It consists of octahedral [Co(NH3)6]3+cation (Co1 site symmetry 1), tetrahedral [ReVIIO4]−anions (Re site symmetry 1) and octahedral [ReIVF6]2−anions (Re site symmetries 1and \overline{3}). The [ReF6]2−octahedral anions (mean Re—F = 1.834 Å), [Co(NH3)6]3+octahedral cations (mean Co—N = 1.962 Å), and the [ReO4]−tetrahedral anion (mean Re—O = 1.719 Å) are slightly distorted. A network of N—H...F hydrogen bonds consolidates the structure. The crystal studied was refined as a two-component twin.